A so called fusion draw machine is an example of a conventionally known apparatus for forming glass in sheet form. The fusion draw machine causes molten glass to flow downward along a forming member to produce a glass ribbon having a predetermined thickness. Individual glass sheets may be cut from the glass ribbon
A more specific example of a known glass forming apparatus of this type is that which is equipped with first peripheral walls that define an inner forming space for forming molten glass into sheet form by surrounding the lateral periphery of the space and having a lower opening at the lower end thereof; a forming means such as a forming member for causing the molten glass to flow downward to form the molten glass into a glass ribbon, provided within the inner forming space; second peripheral walls provided under the first peripheral walls with an interval therebetween that define an inner space for receiving the glass ribbon by surrounding the lateral periphery of the space and having an upper opening through which the glass ribbon passes; and a pair of rollers provided within the second peripheral walls for pinching and drawing the glass ribbon downward.
In a glass forming apparatus having the configuration described above, there are cases in which volatilized components of the molten glass agglomerate on the interiors of the first peripheral walls, into which the molten glass is supplied from the exterior. The agglomerated volatilized components may travel along the inner surfaces of the first peripheral walls as droplets, and drop therefrom. Problems such as formation defects and cracks in the glass ribbon may occur if the agglomerated glass components drop between the glass ribbon and the pair of rollers and are sandwiched therebetween.
Generally, partitioning plates for adjusting the temperatures within the first peripheral walls are provided above the pair of rollers in a glass forming apparatus. There are cases in which the droplets of agglomerated glass travel along the inner surfaces of the first peripheral walls, reach the partitioning plates, travel along the partitioning plates, then drop. It is possible to scrape the agglomerated glass from the surface of the partitioning plates with a rod shaped cleaning member by inserting a cleaning member through the interval between the first peripheral walls and the second peripheral walls.
However, the efficiency of inserting and operating the cleaning member within the narrow interval is extremely poor. In addition, there are cases in which new formation defects or cracks are generated by the cleaning member or by droplets falling during the cleaning operation while performing the difficult task of operating the cleaning member within the narrow interval. Such falling of droplets is unpredictable, and it had conventionally been necessary to constantly monitor the cleaning operation.